Generally, an automatic electronic flash unit, which is employed by a photographer, has a flash lamp as well as a light sensor. The light sensor acts to detect the light reflected from the subject to be photographed and in response to said reflected light controls the duration of the flash so that a proper exposure of the film is obtained. Such an automatic electronic flash unit is very often not effective when operating in a bounced light mode; i.e., the mode of operation where the light flash is aimed at a reflecting surface, such as a ceiling in a room or a wall in a room, because the sensor of such a unit is aimed in the same direction as the light flashes and therefore said sensor is not properly oriented to receive light which has been reflected from the subject being photographed. In such circumstances, since the light, if any, which is detected by the sensor is not light which is reflected from the subject to be photographed, the flash duration is not properly controlled and incorrect film exposure is the normal result.
Now it should be understood that certain automatic electronic flash units, which are generally considered to be expensive, do have the facility of positioning the source of light flash independently of the light sensor. It should be apparent that with this last described structure, the sensor can be aimed at the subject to be photographed while at the same time the source of the light flash can be aimed at a reflecting surface. With this arrangement the light sensor does operate properly to control the duration of the flash and it is not to this type of device that the present invention is directed.
The present invention is directed to a device which is attached to an automatic flash unit or which can be attached to an automatic flash unit and which is relatively fixed with respect to the flash unit. The present invention enables such a unit to be operated in a bounced light mode.